JPH01173087A - Fixing device - Google Patents

Abstract

PURPOSE:To extend the service life until a fixing roller becomes unuseable due to an offset by cleaning the fixing roller by a cleaning member containing a substance whose surface energy is higher than that of a fiber member. CONSTITUTION:A recording material 13 which has carried an unfixed toner image 12 is allowed to pass through between a fixing roller 1 and a pressure roller 4. By a halogen heater 7 controlled to a prescribed temperature, the toner image 12 is fixed onto the recording material 13. In this process, the unfixed toner image 12 which is brought to thermal fixation onto the recording material 13 is offset little by little onto the roller 1, and it is eliminated as follows, by a cleaning device 24. That is, a web 18 is formed by plating heat resistance nonwoven cloth with nickel whose surface energy is higher than said cloth, and it is fibrous, therefore, pressured by a pressure roller 16, and brings the roller 1 to cleaning, while being wound up by a winding roller 17. In such a way, an effect for wiping off a toner becomes high, and the service life of the roller 1 can be extended.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is an image forming apparatus such as a copying machine, a laser beam printer, a magnetic stylus printer, etc., in which an unfixed image is formed on a recording material using a roller. The present invention relates to a fixing device that is used in the field of fixing technology, and particularly includes a cleaning device for cleaning a fixing roller for thermal fixing using a heat roll fixing method.

(Prior Art) In an image forming apparatus such as an electrostatic recording device, an unfixed image formed on a recording material (for example, paper or an OHP sheet) is transferred onto the recording material as a final finishing step of the image forming process. It is necessary to make it take root. A fixing device for this purpose generally uses a heat roll fixing method.

A heat roll fixing type fixing device in a conventional electrophotographic apparatus is a device having a fixing process.

As shown in FIG. 6, a fixing roller l is formed by coating the outer layer of an aluminum core bar 2 with silicone rubber 3 to a predetermined thickness;
A pressure roller 4 is formed by coating the outer layer of an aluminum core 5 with silicone rubber 6 to a predetermined thickness and further applying a resin coating 6' to the surface layer, and these fixing rollers 1 and the pressure roller 4 are provided with a pressure roller 4. It is composed of a heat source 7 and the like provided therein.

According to the fixing device configured as described above, the recording material 13 carrying the unfixed toner image 12 is conveyed between the fixing roller l and the pressure roller 4 by a conveying means (not shown), and the recording material 13 carrying the unfixed toner image 12 is conveyed between the fixing roller l and the pressure roller 4. As a result, the unfixed toner image 12 is heated and fixed onto the recording material 13. At this time, a small amount of toner forming the unfixed toner image 12 on the recording material 13 is transferred to the fixing roller l.
transfer, or offset, to the surface of Since the toner offset to the fixing roller 1 may deteriorate the quality of electrophotographic images, electrophotographic apparatuses are provided with a cleaning device for cleaning the surface of the fixing roller 1. There are various kinds of leaning devices like this.

As shown in FIG. 6, the above-mentioned conventional cleaning device is such that a web 15 made of a fibrous member (for example, Nomex (trade name), etc.) is brought into contact with the web 15, and the fixing roller l is cleaned by the fibrous member. There is something. (Refer to Japanese Patent Application Laid-Open No. 50-57237).

(Problems to be Solved by the Invention) However, especially in a heat roll fixing type fixing device, when the surface of the fixing roller l becomes rough and the mold releasability deteriorates, the surface of the fixing roller l becomes rough. The adhesion with the toner becomes high, and the toner comes to adhere to the surface of the fixing roller l. Therefore, there is a problem in that the web 15 may not be able to completely remove the toner on the fixing roller l from the roller.

In addition, as another conventional cleaning device, a cleaning roller (not shown) made of a metal (for example, aluminum) that has a high affinity with toner is brought into contact with the fixing roller l, and the fixing roller l is cleaned by the cleaning roller. There is something (Japanese Patent Application Laid-Open No. 48-6243
(Refer to Publication No. 5), the surface of such a metal cleaning roller has good toner adsorption properties, and the fixing roller l
Toner adhered to the surface of the roller has a high ability to separate from the surface of the roller.

However, in a cleaning device using such a cleaning roller made of metal, the surface of the cleaning roller is smooth and hard, so that the toner carried in some places on the recording material 13 is offset to the fixing roller l, and furthermore, the cleaning roller is When the toner is attracted to the surface, the toner adheres to the surface of the cleaning roller in some places. As a result, as the toner is attracted to the surface of the cleaning roller, the cleaning roller comes into contact with the fixing roller 1 only in areas where more toner has adhered to the surface of the cleaning roller, resulting in areas that cannot be cleaned in the longitudinal direction of the roller.
Cleaning ability decreases. Further, although the metal constituting the cleaning roller has a high adsorption property to the toner on the fixing roller l, there is a problem in that the metal has a low ability to collect toner from the roller.

The present invention has been made in view of the above circumstances, and its purpose is to improve the ability to remove the developer on the surface of the roller used for fixing unfixed images from the surface of the roller. Another object of the present invention is to provide a fixing device equipped with a cleaning device capable of improving the ability to recover detached developer from the roller, thereby improving the ability to clean the developer on the roller.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a fixing device having a roller for fixing an unfixed image.
It is characterized by comprising a cleaning device that cleans the roller with a cleaning member made of a fibrous member that contacts the roller and contains a substance having a higher surface energy than the fibrous member at least on the side that contacts the roller. shall be.

(Function) In this way, the developer offset to the fixing roller is adsorbed between the fibers of the cleaning member made of a fibrous member, and the high surface energy substances contained in the fibers of the cleaning member are absorbed by the developer. Because of the high affinity of
The cleaning member is able to better absorb the developer on the fixing roller, and its cleaning ability is improved.

(Example) An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a configuration diagram of a fixing device according to the present invention. In the figure, 1 is a fixing roller, which is attached to the outer layer of an aluminum core 2.
TV silicone rubber (low temperature vulcanization type silicone rubber)
3 to a predetermined thickness. A pressure roller 4 is provided below the fixing roller l, which is made by coating the outer layer of an aluminum core 5 with HTV silicone rubber 6 to a predetermined thickness and further coating the surface layer with resin. It is formed by applying a coating 6'.

Further, a halogen heater 7 serving as a heat source is disposed inside the fixing roller 1 and the pressure roller 4. A thermistor 8 is brought into contact with the pressure roller 4, and the thermistor 8 controls whether the supply of current to the halogen heater 7 is turned on or off. In this way, the fixing roller 1
The temperature of the pressure roller 4 and the temperature of the pressure roller 4 are maintained at a predetermined temperature (for example, 170'''C) suitable for fixing the unfixed toner image on the recording material 13. The fixing roller 1 and the pressure roller 4 are rotated in the direction of the arrow in the figure by a drive device (not shown).

On the other hand, in order to improve the releasability of toner from the fixing roller l, a release agent application device 9 is provided at a predetermined location of the fixing device. This release agent application device 9 is configured to apply silicone oil lO in an oil tank to the fixing roller l via a felt 11.

Furthermore, a cleaning device 24 for cleaning toner offset on the fixing roller 1 is provided at a predetermined location of the fixing device. This cleaning device 24 cleans the fixing roller I with a web 18 made of a nickel-plated fibrous cleaning web that is brought into contact with the fixing roller I by a pressure roller 16. This nickel-plated web 18 is made by plating the conventional heat-resistant non-woven fabric Nomex (trade name) with nickel, a substance with higher surface energy than Nomex, using an electroless plating method. coated with nickel.

The nickel-plated web 18 thus constructed is sent in the direction of arrow C in the figure by the feed roller 14 and taken up by the take-up roller 17.

Next, the operation of the fixing device configured as described above will be explained.

The recording material 13 carrying the unfixed toner image 12 is conveyed by an unillustrated device in the direction of arrow a in FIG. It is passed between the pressure roller 4 and the halogen heater 7.
The unfixed toner image 12 carried on the recording material 13 is fixed onto the recording material 13 by heat controlled to a predetermined temperature and supplied from the fixing roller 1 and the pressure roller 4 through the fixing roller 1 and the pressure roller 4.

In the above-mentioned thermal fixing process, the unfixed toner image 12 that is thermally fixed onto the recording material 13 is offset little by little to the fixing roller l, and the offset toner is removed from the fixing roller l by the cleaning device 24 as follows. removed.

That is, the nickel-plated web 18 is pressed by the pressure roller 16 and wound around the take-up roller 17 at a predetermined speed (for example, 1 mm per 100 sheets of recording material), and the nickel-plated web 18 is rolled up by the fixing roller It is rubbed against the surface of the fixing roller 1 as the roller l rotates,
The surface of the fixing roller is cleaned.

In this case, since the nickel-plated web 18 is fibrous, it has good contact with the fixing roller l, unlike a smooth and hard cleaning member such as a metal roller.
As shown in FIG. 2, the toner 23 offset in some places on the surface of the fixing roller l is adsorbed between the fibers #i22 of the web 18, so that there is no local accumulation of toner, and the fixing roller The contact condition between the nickel-plated web 18 and the nickel-plated web 18 is good. 1. Since the web 18 is fibrous, it is highly effective in wiping off toner from the roller.

Further, the nickel contained in the side of the nickel-plated web 18 that contacts the fixing roller 1 adsorbs the toner on the fixing roller 1 well because metals such as nickel have high surface energy and high affinity with toner. As a result, the cleaning ability of the cleaning device 24 to remove toner from the fixing roller l is significantly improved compared to the conventional web. Therefore, as the releasability of the surface of the fixing roller l is reduced, the toner becomes strongly adhered to the surface of the fixing roller l, or such toner can be easily removed.

Furthermore, when the nickel-plated web 18 is rubbed against the surface of the fixing roller l, nickel adhering to the fibers of the nickel-plated web 18 falls off to an appropriate extent and stays in the rubbing area. The nickel that falls off from the fibers and stays in the rubbing area is in the form of particles, and these nickel particles are
acts as an abrasive on the surface of the fixing roller 1, and scrapes off the toner offset on the surface of the fixing roller 1.Also, during this polishing, the abrasive particles are metal with higher surface energy than fibers, so the affinity with the toner is reduced. Due to the height, the metal abrasive particles roll on the surface of the fixing roller l between the fibers, and the toner scraped off from the surface of the metal particles and the roller is strongly adsorbed.

Therefore, if the surface of the fixing roller 1 is made of rubber such as silicone rubber or fluorine rubber, the offset toner may penetrate into the surface layer of the rubber, but the surface layer of the rubber is scraped due to the abrasive effect of the metal particles mentioned above. Therefore, the offset toner is reliably separated from the roller. The offset toner 23 separated from this roller is attracted between the fibers 22 of the web 18 and carried away, as shown in FIG. Therefore, toner does not accumulate in the contact area between the fixing roller 1 and the web 18, and the surface layer of the roller is always kept clean. The nickel coating provides a higher polishing effect than conventional webs.

Furthermore, since it is a metal coating, toner adsorption properties are increased. These properties are combined, that is, the toner on the surface of the fixing roller 1 is ground by the nickel web 18, adsorbed and collected, and effective cleaning is performed.

As described above, the life of the fixing roller l until it becomes unusable due to toner offset can be significantly improved compared to the conventional method.

According to durability tests, a conventional cleaning device using a web could only fix 80,000 sheets before the fixing roller became unusable due to offset, whereas the cleaning device of the present invention using a nickel-plated web With the cleaning device, the number of sheets fixed reached the aforementioned 200,000 sheets, and we were able to significantly extend the life of the fixing roller.

In particular, the fixing device cleaning device according to the present invention can form color images*! It is effective in the fixing device of The fixing device shown in FIG. 1 is particularly effective in the fixing step in color image formation, and various toners of yellow, magenta, cyan, and black are laminated in multiple layers on the recording material 13. In this type of color image formation, in order to reproduce colors close to those of the original document, multiple layers of toner are heated and melted to mix colors, so toner with a low softening point (that is, a low melting point) and a sharp melting point is used. need to use. Since it is necessary to have a low melting point, it is not possible to mix in a large amount of wax that improves the releasability of the toner, but this is because wax has a high melting point.

In this case, the sharp melt toner tends to be offset by the roller, and the toner layer to be fixed is thick due to the stacking of multiple colors, so it is easy to offset, and furthermore, the multiple toners that make up the color toner each have different components. Therefore, the effects of changes in the environment and the like are slightly different for each toner, and offset is more likely to occur in a fixing device that performs constant temperature control.

For this reason, the surface material of the fixing roller of the fixing device in color image formation is particularly limited, and from the viewpoint of release properties, fluororesin-based materials such as Teflon (trade name) used in conventional monochrome image fixing devices are used. Since it is difficult to use a suitable material, silicone rubber or silicone resin as shown in FIG. 1 is used. Further, among silicone rubbers, RTV (room temperature vulcanizable silicone rubber) is particularly preferable because fluororesins are not compatible with mold release agents such as silicone oil that prevent offset. Therefore, the roller surface layer is preferably a silicone type that is active against silicone oil.

In particular, those impregnated with oil are more preferable.

In such a combination of sharp melt toner and fixing roller l made of silicone rubber, not only is the adhesion between the sharp melt toner and the silicone rubber high, but also the toner melted by heat penetrates into the silicone rubber and is difficult to fix. This changes the quality of the rubber surface layer of the roller 1, which deteriorates the releasability of the fixing roller 1.

The present invention is particularly effective in the fixing device of the color image forming apparatus described above.

When we conducted a durability test using the fixing device shown in Figure 1, we found that
In a conventional cleaning device using a web made of Nomex, the number of sheets to be fixed before the fixing roller became unusable due to offset was 8,000 sheets, whereas in the cleaning device of the present invention using a nickel-plated web, the number of sheets fixed was 8,000. The number of sheets fixed reached 50,000 sheets, and the lifespan of the fixing roller was significantly extended.

The color toner used in color image formation will be described below.

Color toner is produced by melting, mixing, pulverizing, and classifying polyester resin, styrene-acrylic resin, colorant (dye, sublimable dye), charge control agent, etc., for example. If necessary, an external addition step of adding various external additives to the toner may be added.

The average particle size of the toner is usually 5 to 30 JLm. In consideration of offset resistance, fixing properties, and sharp melt properties, color toners using polyester resin as a binder resin are particularly preferable.

A sharp-melt polyester resin is a high molecular compound having an ester bond in the main chain of the molecule, which is synthesized from a diol compound and a dicarboxylic acid.

Examples of diol components include ethylene glycol, 1
．． 2-propylene glycol, l,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butynediol, 1,4-bis(hydroxymethyl)cyclohexane, bisphenol A, hydrogenated bisphenol A, poly Bisphenol type diols such as oxyethylated bisphenol AI and polyoxypropylenated bisphenol A are mentioned.

Examples of the dicarboxylic acid component include aliphatic dicarboxylic acids or aromatic dicarboxylic acids such as maleic acid, fumaric acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, cohelic acid, adipic acid, sepacic acid, malonic acid, and oxalic acid; and esters with acid anhydrides or lower alcohols.

The softening point of the sharp melt polyester resin used in the present invention is 60 to 150°C, preferably 80 to 120°C.
C is good, and the polyester resin has a weight average molecular weight (Mw) of 4000 to 200.000, preferably 4.
000 to 100,000 and the number average molecular weight (M n
) is 2500-7000, preferably 3000-500
0 (provided that Mw≧Mn) is preferable, and it is further preferable that the Mw/Mn of the polyester resin is 7 or less (more preferably 6 or less).

That is, when the average molecular weight is below the specified range, the molecular weight is too low and blocking or offset occurs, and when it is above the specified range, the fixing temperature becomes too high to be of practical use. In addition, M w / M of polyester resin
If n is 7 or more, sharp melt will not be exhibited and color mixing will be insufficient.

The softening point in the present invention is the temperature T measured by the method below. It refers to the value subjected to measurement, and may be changed in consideration of the measurement method according to the present invention.

That is, using a flow tester CFT-500 type (manufactured by Shimabara Seisakusho), with a die (nozzle) diameter of 0.5 mm and thickness of 1.0 mm, an extrusion load of 50 kg was applied, the initial temperature was set at 80°C, and the preheating time was 300 seconds. Thereafter, a toner plunger drop amount-temperature curve (hereinafter referred to as a softening S-curve) is determined when the humidity is increased at a constant rate of 5° C./min.

The sample toner used was 1 to 3 g of purified fine powder, and the plunger cross-sectional area was 1.0 cm.The softening S-shaped curve was normally as shown in Figure 5.As the temperature was raised at a constant rate of 0, The toner is gradually heated and begins to flow out (plunger descends A→B), and as the temperature rises further, the molten toner begins to flow out significantly (84C→D), and the plunger stops descending (D→D). E).

The height H of the S-curve indicates the total outflow amount, and the temperature T0 corresponding to the 0 point of H/2 indicates the softening point of the toner.

The sharp melt resin in the present invention is defined as T, where the temperature at which the melt viscosity shows io'cp is Tt, and the temperature at which the melt viscosity shows 5X10'cp is T3, = 100 to 150 @ CI
ΔT l = l Tt - Tt l = 5~30'''
Refers to a resin that satisfies condition C.

Melt viscosity measurement can be carried out using a high-viscosity B-type rotary machine equipped with a constant temperature bath (for example, product name Viscon-) fl (-Dell, VC-250, Toyo Seisakusho Co., Ltd. Department) that can control the temperature of the sample and rotor. This can be carried out using a viscometer (for example, R8 type 1 manufactured by Tokyo Keiki Co., Ltd.) with rotor No. 4 or No. 5.

Sharp-melt resins having these temperature-melt viscosity characteristics are characterized by an extremely sharp decrease in viscosity when heated. Such a viscosity reduction causes proper mixing of the uppermost toner layer and the lowermost toner layer, and also rapidly increases the transparency of the toner layer itself, resulting in good subtractive mixing.

For example, toners using resins with a T□ of 1006C or less easily cause blocking and have shortcomings in storage stability.
If it is more than that, the color mixing property will be poor and the fixing property will also be difficult.

Further, as an optional component, a material used as a binder resin for toner can be appropriately mixed. For example, a styrene-alkaline acid ester copolymer.

Styrene-methacrylate copolymer, polyvinyl chloride, natural resin-modified phenol, natural resin-modified maleic acid resin, polyvinyl acetate, silicone resin, polyurethane, polyamide resin, ionomer resin, furan resin, epoxy resin, xylene resin, Polyvinyl butyral, terpene resin, coumaron indene resin, petroleum resin, chlorinated paraffin, etc. can be used as appropriate.

Colorants used in toner include carbon black, nigrosine dye, lamp black, Sudan black SM,
First Yellow G, Benzidine Yellow 1 Picment Kai Yellow, India First Orange, Irgadine Red, Valanitroaniline Red, Toluidine
Red, Carmine FB, Permanent Bordeaux FRR
, Pigment Orange R1 Linole Red 2G, Lake Red C, Rhodamine FB, Rhodamine B Lake, Methyl Violet B Lake, Phthalocyanine Blue, Pigment Blue, Prilliant Green B, Phthalocyanine Green, Oil Yellow GG, Zapon・
First Yellow CGG, Kayaset Y963, Kayaset YG, Sumiplast, Yellow G, Zapon First Orange RR, Oil Scarlet, Sumiblast Orange G, Orazole Brown B, Pomegranate First Scarlet CG, Eisens Viron Red BE
H, oil pink OP etc.

Next, a modified embodiment of the present invention will be described with reference to FIG.

FIG. 3 is a block diagram of a modified embodiment of the fixing device according to the present invention. In the figure, reference numeral 19 denotes a cleaning roller covered with a nickel-plated web similar to the nickel-plated web 18 in the first embodiment. The cleaning roller 19 is a cylindrical roller 2 made of aluminum as shown in FIG.
0, a nickel-plated web 2 constructed in the same manner as the nickel-plated web 18 in the first embodiment
1 is adhesively wound.

The cleaning roller 19 is rotated in the direction of arrow d in the figure by a drive device (not shown). Further, the other configurations are the same as those of the first embodiment described above.

According to the modified embodiment described above, the cleaning roller 19
The fibers 21 whose surface layer is plated with nickel are rubbed against the surface of the fixing roller 1 as the fixing roller 1 rotates, thereby cleaning the surface of the fixing roller 1. The cleaning roller 19 rotates at a predetermined circumferential speed (for example, 1 mm per 100 sheets of recording material). In this way, this modified embodiment also provides the same effects as the first embodiment described above. Incidentally, when a durability test was actually conducted on this modified example, the same cleaning effect as the first example was obtained.

In each of the above-described embodiments, a nickel-plated web made of Nomex plated with nickel was used as the cleaning member, but the present invention is not limited to this, and the cleaning member may be a nickel-plated web made of Nomex. It is also possible to use a material plated with copper, which is a material with high surface energy.
When a durability test was conducted on a fixing device equipped with a cleaning device using such a cleaning member for a copper-plated web, the same effects as in the case of a nickel-plated web were obtained. However, once used for cleaning, nickel falls from the fibers and toner adsorbs to the nickel, reducing the cleaning power the next time. Therefore, as shown in Figure 1, the cleaning material should be disposable rather than reused. It is preferable to

Further, the method for manufacturing a nickel-plated web by plating Nomex with nickel is not limited to the electroless plating method described above, and other methods may also be used. The metal coating may be applied to the web by using not only the plating method but also a thermal spray molding method or the like.

Furthermore, as metals contained in the fibers, it is of course possible to use aluminum, copper, etc., but when silicone rubber is used for the surface layer of the roller and sharp melt toner is used as the toner, it has been experimentally shown that nickel is more suitable. Ta.

(Effects of the Invention) As described above, according to the present invention, in a fixing device having a roller for fixing an unfixed image, the fixing device includes a fibrous member that contacts the roller, and that contacts at least the roller. A cleaning device for cleaning the roller with a fibrous cleaning member containing a substance having a higher surface energy than that of the male member is provided on the side of the male member. It is possible to increase the force with which some developer is separated from the surface of the roller, and it is also possible to improve the ability to collect the separated developer from the roller, thereby improving the ability to clean the developer on the roller, and to improve the ability to clean the developer on the roller. This has the effect of extending the lifespan until it becomes unusable due to offset.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a fixing device according to the present invention, FIG. 2 is a diagram showing the adsorption state of toner between fibers of a nickel-plated web, FIG. 3 is a block diagram of a modified embodiment of the present invention, and FIG. 5 is a perspective view of a cleaning pipe covered with a nickel-plated web, FIG. 5 is a graph showing a softening curve of a flow tester, and FIG. 6 is a configuration diagram of a conventional fixing device. l...Fixing roller, 4...Pressure roller, 12...
Unfixed toner image, 13... Transfer material (recording material), 18° 21... Nickel plated web (cleaning member)
, 19... cleaning roller, 24... cleaning device.

Claims (4)

[Claims] (1) A fixing device having a roller for fixing an unfixed image, comprising a fibrous member that contacts the roller, and containing a substance having a higher surface energy than the fibrous member at least on the side that contacts the roller. 1. A fixing device comprising a cleaning device that cleans the roller using a cleaning member consisting of a roller. (2) The fixing device according to claim 1, wherein the roller is an elastic body whose layer in contact with the unfixed image is made of silicone rubber. (3) The fixing device according to claim 1, wherein the fixing device fixes a plurality of developers having different compositions onto the recording material at once. (4) The fixing device according to claim 3, wherein the plurality of developers having different compositions form a layered structure.